This invention relates to trailer hitches, and more particularly to a device for aiding the operator of a towing vehicle in backing the towing vehicle into registry with the trailer hitch component on the trailer.
Many types of trailer hitching aids have been proposed heretofore. One type utilizes a flexible line between the towed and towing vehicles and senses the angle of the line relative to the towing vehicle to instruct the operator how to maneuver the towing vehicle into alignment. A proximity sensor is used to indicate when hitch components are in vertical alignment. Typical of this type of aid are those disclosed in U.S. Pat. Nos. 3,938,122 and 4,187,494.
Another type of hitching aid proposed heretofore utilizes a light beam on a towed vehicle to align with a target on a towing vehicle, the position of the light on the target directing the operator to bring the towing vehicle into alignment with the towed vehicle. This type is exemplified by U.S. Pat. Nos. 3,901,536 and 4,552,376.
Still another type of hitching aid proposed heretofore utilizes an electric signal beam transmitted from a towed vehicle to one or more receivers on a towing vehicle, the angle of the beam providing direction guidance and a proximity sensor identifying when the hitch components are in vertical alignment. This type is exemplified by U.S. Pat. Nos. 3,924,257 and 4,627,511.
Another type of hitching aid proposed heretofore utilizes a variable resistor on a towing vehicle, and feelers extend from the rotatable arm of the resistor for engagement by the tongue of a towed vehicle, the angle of the feeler guiding the operator to move the hitch component on the towing vehicle into registry with the hitch component on the towed vehicle. This type is exemplified by U.S. Pat. No. 4,122,390.
Also proposed heretofore are a wide variety of types of arms mounted one on a towing vehicle and another on a towed vehicle, the operator being required to maneuver the towing vehicle to bring the pair of arms into close proximity to align the hitch components. This type is difficult to use at night and it is subject to severe inaccuracies because of optical parallax and the general conditions of sight of various operators.
There also are various tracking systems by which a following vehicle may track the direction and distance from a leading vehicle or from a target object. These cannot operate to bring hitch components into vertical registry however. These are illustrated by U.S. Pat. Nos. 2,188,293; 3,046,549; and 4,710,020.
All of the foregoing types of aids are characterized by one or more of such limitations and disadvantages as requiring mechanical linkages between vehicles, introduction of errors of parallax and visibility, and involving the complexity and cost of separate electrical components for direction and distance detections.